Disabling TLS 1.0 Windows Server 2008-2012 – Exchange – PCI 3.1 Scan

 

If you have to comply to recent PCI standards, a PCI scan on your Exchange server might reveal that it’s no longer compliant because TLS 1.0 is still enabled on it and you need to disable TLS 1.0 to pass test.  This applies to Exchange 2010, 2013 and 2016.  Not sure about 2007…

Tried the following on two implementions and had no issues.  Has been running fine for a while.

To pass PCI 3.1 test you need to disable TLS 1.0 on Windows server.  If you disable it, Outlook on Windows 7/8 machines will not work, it will show disconnected.  You might not be able to delete items, Auto-discover won’t work….This applies to Outlook on Windows server 2008, 2008 r2 and 2012.

In short, you will have to disable TLS on the Windows server running exchange (done through registry setting – the tool below will do it for you), make sure your  Windows7/8 has a certain update installed, that came out in 2016 (obtained through Windows Updates) and it also applies to servers 2008 and 2012.  The update adds support for TLS 1.1 and 1.2 but doesn’t enable them automatically, and lastly make changes to the registry on those client machines to enable TLS 1.1 and 1.2.  Very straight forward as will explain below.

Windows 10 clients don’t need any updates or changes since TLS 1.1 and 1.2 is supported and enabled out of the box.

Here are the details:

Before you start:

1- Apply latest Windows updates to Windows server including Updates for Exchange server.  As of this article, Cumulative Update 20 (CU 20) for Exchange 2013 is available.  You don’t need to be at CU 20, but I usually cover all bases in case I overlook updates.

2- You should update Windows 7/8 machines and Server 2008, 2008 R2 and Server 2012 – Windows Updates.  There is an update that came out in 2016 to enable TLS 1.1 and TLS 1.2 – chances are you have it unless you never updated Windows or never checked.

http://catalog.update.microsoft.com/v7/site/search.aspx?q=kb3140245

3- as always have a good back up of your server..

Action:

Disable TLS 1.0 on the Windows server running Exchange.  There is a tool called IISCrypt, download it.

https://www.nartac.com/Products/IISCrypto

Run it on the Exchange server.  Under Templates choose PCI 3.1.  Apply and reboot your Exchange.  Now Exchange has TLS 1.0 disabled and if you run the PCI 3.1 scan you should pass on TLS 1.0

BUT with disabling TLS 1.0 on that server, you won’t be able to remote/RDP into it from Windows 7/8 machines (You will however be able to do that from Windows 10 machines) Outlook on Windows 7/8 machine won’t connect.  To make it work do the following:

Copy the following text(marked in bold) into a notepad and save it as something like “EnableTLS1.1-1.2.reg“.

 

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 2.0]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 2.0\Client]
“DisabledByDefault”=dword:00000001

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client]
“DisabledByDefault”=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client]
“DisabledByDefault”=dword:00000000

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\WinHttp]
“DefaultSecureProtocols”=dword:00000A00  

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Internet Settings\WinHttp]
“DefaultSecureProtocols”=dword:00000A00  

 

Double click on this file on the Windows 7/8 machines and it should add all necessary registry keys to enable TLS 1.1 and 1.2.

Reboot Windows 7/8.  Outlook should work normally now.

You don’t need to do anything for Windows 10 machines.

You might have issues with older smart phones and Email.

Make sure you don’t have any third part applications that communicate with Exchange with TLS 1.0.  Look for applications updates.  Consult third party support.

 

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